The top hose on the fuel petcock is a vacuum line to operate the fuel pump diaphragm. It should go into a nipple on the choke side of the carb. I don't think you should plug that hose coming down from the left side of the carb. It is a vent. What position do you have the fuel petcock in? If it is horizontal for more than a minute, gas will overflow onto the ground. It is meant to be a float bowl primer. Once the float bowl is full of gas, you need to put it in the "on"position. The vacuum of the engine will then pump fuel as the engine is running. Hope I didn't get off the subject.